1 Progress on the 30m Giant Segmented Mirror Telescope AURA New Initiatives Office Leiden, 17 May 2001 Matt Mountain Jim Oschmann Knut Olsen

2 GSMT Partnership between Gemini, NOAO and our communities Science Enabled Implementation Concepts Resources Interfaces Issues

3 Science & Instrument workshops Madison MAXAT science Woods Hole MAXAT technology Tucson MAXAT instruments Tucson GSMT science – 2000 Subsystem working group meetings Systems, optics, structures… OPTICON, Edinburgh, Leiden

4 GSMT System Considerations - Astronomers View Science Mission - DRM’s GSMT Concept (Phase A) Support & Fabrication Issues Active Optics (aO) Site Characteristics Enclosure protection Adaptive Optics Instruments Full System Analysis

5 Derived Top Level Requirements

6 30m Giant Segmented Mirror Telescope concept 30m F/1 primary, 2m adaptive secondary GEMINI

7 The Enemies….. Wind….. The Atmosphere……

8 Enabling techniques Active and Adaptive Optics Active Optics already integrated into Keck, VLT and Gemini Adaptive Optics “added” to Keck, Gemini (and soon) VLT  Active and Adaptive Optics will have to be integrated into GSMT Telescope and Instrument concepts from the start

9 GSMT Control Concept LGSs provide full sky coverage Deformable M2 : First stage MCAO, wide field seeing improvement and M1 shape control 10-20’ field at ” seeing 1-2’ field fed to the MCAO module  M2: rather slow, large stroke DM to compensate ground layer and telescope figure,  or to use as single DM at >3  m. (~8000 actuators)  Dedicated, small field (1-2’) MCAO system (~4-6DMs). Focal plane Active M1 (0.1 ~ 1Hz) 619 segments on 91 rafts

10 AO Technology constraints (50m telescope) r 0 (550 nm) = 10cm No. of Computer CCD pixel Actuator pitch S(550nm) S(1.65  m) actuators power rate/sensor (Gflops) (M pixel/s) 10cm 74% 97% 200,000 9 x cm 25% 86% 30,000 2 x cm 2% 61% 8,000 1, SOR (achieved) 789 ~ 2 4 x 4.5 Early 21 st Century technology will keep AO confined to > 1.0  m for telescopes with D ~ 30m – 50m

11 MCAO on a 30m: summary MCAO on 30m telescopes should be used  m Field of View should be < 3.0 arcminutes, Assumes the telescope residual errors ~ 100 nm rms Assumes instrument residual errors ~ 70 nm rms –Equivalent Strehl from focal plane to detector/slit/IFU > 1 micron –Instruments must have: very high optical quality very low internal flexure (  m) Delivered Strehl ~ ~ ~ Sodium laser constellation 4 tip/tilt stars (1 x 17, 3 x 20 Rmag) PSF variations < 1% across FOV Rigaut & Ellerbroek (2000)

12 AO an integral part of the GSMT Concept Low order correction for wind buffeting and “seeing improvement” –3 Natural Guide stars give full sky coverage Narrow Field AO requires at least one LGS for  m –Science requires low emissivity implementation MCAO requires multiple NGS and multiple DM’s

13 Comparative performance of a 30m GSMT with a 6.5m NGST Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration GSMT advantage NGST advantage R = 10,000 R = 1,000 R = 5

14 Comparative performance of a 30m GSMT with a 6.5m NGST Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration OWL advantage NGST advantage R = 10,000 R = 1,000 R = m 

15 GSMT Implementation concept - wide field (1 of 2) Barden et al (2001)

16 Optical “seeing improvement” using low order AO correction 16 consecutive nights of adaptive optics the CFHT Image profiles are Lorenzian

17 GSMT Implementation concept - wide field (2 of 2) 20 arc minute MOS on a 30m GSMT ” fibers R=1, nm – 650nm R=5, nm – 530nm Detects 13% - 23% photons hitting 30m primary 1m Barden et al (2001)

18 GSMT Implementation concept - MCAO/AO foci and instruments MCAO optics moves with telescope Narrow field AO or narrow field seeing limited port MCAO Imager at vertical Nasmyth elevation axis 4m Oschmann et al (2001)

19 Spot diagrams for MCAO + Imager Diffraction limited performance for 1.2  m – 2.2  m can be achieved

20 MCAO Optimized Spectrometer Baseline design stems from current GIRMOS d-IFU tech study occurring at ATC and AAO –~2 arcmin deployment field – µm coverage using 6 detectors IFUs –12 IFUs total ~1.5”x1.5” field –~0.05” spatial sampling R ~ 6000 (spectroscopic OH suppression)

21 GSMT Implementation concept - MCAO/AO foci and instruments MCAO optics moves with telescope Narrow field AO or narrow field seeing limited port MCAO Imager at vertical Nasmyth elevation axis 4m Oschmann et al (2001)

22 GSMT Implementation concept - MCAO/AO foci and instruments MCAO optics moves with telescope Narrow field AO or narrow field seeing limited port MCAO Imager at vertical Nasmyth elevation axis 4m Oschmann et al (2001)

23 High resolution, high Signal/Noise observations Detecting the molecular gas from gaps swept out by a Jupiter mass protoplanet, 1 AU from a 1 M O young star in Orion (500pc) (Carr & Najita 1998) GSMT observation ~ 40 mins (30 mas beam)

24 8,960 actuators, 30cm spacing on Primary 3,225 actuators, 50cm spacing 50cm actuator pitch Good conditions (0.5" seeing): lambda diameter["] %energy cm actuator pitch Good conditions (0.5" seeing): lambda diameter["] %energy GSMT will need an Adaptive Secondary

25 Sky coverage and Strehl for narrow field, thermal infrared observations using an adaptive secondary (wind buffeting on M1) (Rigaut, 2001)  for  m single laser beacon required

26 End-to-End Approach Science Requirements (including instruments) Error Budget Enclosure concept –Interaction with site, telescope and budget Telescope structure –Interaction with wind, optics and instruments Optics –Interaction with telescope, aO/AO systems and instruments AO/MCAO –Interaction with telescope, optics, and instruments Instruments –Interaction with AO and Observing Model Observing Model

27 Wind Loading Driving characteristic may be wind –Lower wind sites with good seeing –How to protect telescope Enclosure needs May be more limiting than local seeing to performance Cost drivers Advance methods for correcting More critical than for existing telescopes

28

29 Average pressure PSD DATA - effect of enclosure shutters

30 average pressure PSD by EL  Note: No elevation dependence on average pressure on primary

31 How to scale to 30 meters: Average pressure SF (C00030oo) D(d) = d M RMS pressure differences Spatial scale

32 An enclosure is essential: scaled up and taller variation of JCMT Enclosure

33 30m Giant Segmented Mirror Telescope concept Horizon Pointing - Mode 1 = 2.16 Hz

34 Response to Wind Current concept will now go through “second iteration” of design In response to wind analysis

35 Point Design Initial Analysis Finite element model of structure –Gravity sag and initial modal analysis Wind PSD’s calculated from Gemini tests –To be applied to current model Structure function approach to scaling Gemini data on wind buffeting to 30 meter –Preparing to apply wind buffeting to point design Aid in systems flow down of requirements Early trades possible soon

36 Objectives: Next 2 years Develop point design for GSMT & instruments –Carried out within NIO Attack key technical problems –Adaptive optics –Wind loading –Mirror segment fabrication Continue community involvement in defining: –Science & technical requirements –Instrumentation options; technology paths Support design studies that complement other projects (CELT, FELT, OWL, etc.)

37 Resources: Next 2 years Combined Gemini partnership + NOAO resources: $2.1M Core NIO effort focused on studies to: – Analyze point design – Attack key technical issues – Develop instrument and subsystem concepts – Explore science and instrument requirements Additional US National efforts: $2.0M external studies: – Enable community efforts: science; instruments + Study contracts + Broad community workshops – Enable key external engineering studies; alternate concepts + End-to-end system model + detailed error budget + Alternate system design concept studies + Alternate AO system design and modeling studies + Develop site testing equipment; apply in Chile

38 AURA New Initiatives Office Adaptive Optics Francois Rigaut (Gemini)

39 GSMT STEERING COMMITTEE John CasaniJet Propulsion Laboratory Alan DresslerCarnegie Observatory Richard EllisCalTech Bob FugateStarfire Optical Range Jay GallagerUniversity of Wisconsin Bob Gehrz University of Minnesota Riccardo GiovanelliCornell University Bob KirshnerHarvard-Smithsonian, CfA Rolf KudritzkiUniversity of Hawaii Simon LillyHIA Joe Miller University of California Jerry NelsonUniversity of California Larry RamseyPenn State University Chuck SteidelCalTech Present Members

40 Interfaces Community task groups; workshops NSF, other Gemini Agencies (PPARC, NRC, ARC..) Potential partners: CELT; ESO; others Other next generation telescope projects Private sector/government lab consultants NIO steering committee US System steering group –GSMT is the apex of US system –System must support GSMT OPTICON